Ballistic-phonon heat conduction at the nanoscale as revealed by time-resolved x-ray diffraction and time-domain thermoreflectance

M. Highland, B. C. Gundrum, Yee Kan Koh, Robert S Averback, David G Cahill, V. C. Elarde, J. J. Coleman, D. A. Walko, E. C. Landahl

Research output: Contribution to journalArticlepeer-review

Abstract

We use time-resolved measurements of the evolution of surface and buried layer temperatures to quantify the contribution of ballistic phonons to heat transport on nanometer length scales. A laser pulse heats a 100 nm thick Al film which cools by conduction into a GaAs substrate. The top 120-250 nm of the GaAs substrate is doped with In to create a buried layer with a distinct lattice constant. The cooling of the Al film is monitored by time-domain thermoreflectance and, in the second set of experiments, the heating and cooling of the GaAs:In buried layer are monitored by time-resolved x-ray diffraction. The combination of these data shows that thermal transport by ballistic phonons accounts for nearly 20% of the heat flow across the buried layer on nanosecond time scales.

Original languageEnglish (US)
Article number075337
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume76
Issue number7
DOIs
StatePublished - Aug 22 2007

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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